curriculum/challenges/english/blocks/learn-classes-and-objects-by-building-a-sudoku-solver/6606d9d92fcf78598b3b5184.md
A tuple can be unpacked, meaning that the elements contained in the tuple can be assigned to variables, like this:
spam = ('lemon', 'curry')
item1, item2 = spam
In the example above, item1 would have the value 'lemon' and item2 would have the value 'curry'.
Inside the method, delete pass and unpack the empty tuple into row and col.
You should delete pass and unpack the empty tuple into row and col.
({ test: () => assert(runPython(`_Node(_code).find_class("Board").find_function("is_valid").find_body().is_equivalent("row, col = empty")`)) })
class Board:
def __init__(self, board):
self.board = board
def find_empty_cell(self):
for row, contents in enumerate(self.board):
try:
col = contents.index(0)
return row, col
except ValueError:
pass
return None
def valid_in_row(self, row, num):
return num not in self.board[row]
def valid_in_col(self, col, num):
return all(self.board[row][col] != num for row in range(9))
def valid_in_square(self, row, col, num):
row_start = (row // 3) * 3
col_start = (col // 3) * 3
for row_no in range(row_start, row_start + 3):
for col_no in range(col_start, col_start + 3):
if self.board[row_no][col_no] == num:
return False
return True
--fcc-editable-region--
def is_valid(self, empty, num):
pass
--fcc-editable-region--
puzzle = [
[0, 0, 2, 0, 0, 8, 0, 0, 0],
[0, 0, 0, 0, 0, 3, 7, 6, 2],
[4, 3, 0, 0, 0, 0, 8, 0, 0],
[0, 5, 0, 0, 3, 0, 0, 9, 0],
[0, 4, 0, 0, 0, 0, 0, 2, 6],
[0, 0, 0, 4, 6, 7, 0, 0, 0],
[0, 8, 6, 7, 0, 4, 0, 0, 0],
[0, 0, 0, 5, 1, 9, 0, 0, 8],
[1, 7, 0, 0, 0, 6, 0, 0, 5]
]
gameboard = Board(puzzle)